Top Afghan officials have presided over murders, abduction, and other abuses with the tacit backing of their government and its western allies, Human Rights Watch says in a new report.

A grim account of deaths, robbery, rapes and extrajudicial killings, Today We Shall All Die, details a culture of impunity that the rights group says flourished after the fall of the Taliban, driven by the desire for immediate control of security at almost any price.

“The rise of abusive political and criminal networks was not inevitable,” the report said. “Short-term concerns for maintaining a bulwark against the Taliban have undermined aspirations for long-term good governance and respect for human rights in Afghanistan.”

The report focuses on eight commanders and officials across Afghanistan, some of them counted among the country’s most powerful men, and key allies for foreign troops. Some are accused of personally inflicting violence, others of having responsibility for militias or government forces that committed the crimes.

Kandahar’s most powerful commander, the former head of the intelligence service and a key northern governor are among those implicated. All of the accused have denied the allegations against them.

Some have ties to the former president Hamid Karzai, who as early as 2002 warned that security would be his first priority. “Justice [is] a luxury for now; we must not lose peace for that,” the report quotes him saying soon after coming to power. While he was in office, a blanket amnesty law for civil war-era crimes was passed.

There are also multiple links to America’s military and government, sometimes beyond the liaisons that were essential for troops on the ground.

When Assadullah Khalid, the former head of the country’s spy agency, was badly injured in a Taliban assassination attempt, Barack Obama and the former defence secretary Leon Panetta both went to visit him in the American hospital where he was recovering.

In doing so they chose to ignore a long history of accusations of rape, torture, corruption and illegal detentions, some of it from US diplomats or their allies, detailed in the HRW report.

A confidential Canadian government report from 2007 warned that “allegations of human rights abuses by [Khalid] are numerous and consistent” and he was described as “exceptionally corrupt and incompetent” in a leaked US embassy cable.

Khalid has previously dismissed the allegations against him as fabrications. “I know there is nothing (in terms of evidence),” he said in 2012, when his nomination as spy chief stirred up controversy about his past. “This is just propaganda about me.”

Another favourite of US forces, Kandahar’s police chief Abdul Razziq, was pictured last year arm in arm with a beaming three-star US general, who credited him with improving security in the political and cultural heart of southern Afghanistan.

Hamid Karzai accepts the Freedom award from the International Rescue Committee in New York, 2002. The president said he would make security his first priority after he came to power. Photograph: Mark Lennihan/AP

Yet his rise to power he has been dogged by a trail of allegations of extrajudicial killings, forced disappearances and torture, some described by HRW in gruesome detail. As early as 2006, when still leading a unit of border police, he was accused of the abduction and murder of 16 men, said to be in a revenge killing for the death of his brother.

“The acting commander of border police in Kandahar, Abdul Razzaq Achakzai [Raziq], has acknowledged killing the victims, but has claimed (claims now proved false) that the killings took place during an ambush he conducted against Taliban infiltrators,” a report by the office of the EU envoy to Afghanistan said then.

Since he took control of the province’s police in 2011, the United Nations has documented “systematic” use of torture in Kandahar’s police and intelligence units, and the Human Rights Watch report lists multiple cases of men detained by Kandahar police, whose mutilated corpses were found discarded days later. Raziq has repeatedly denied all allegations of wrongdoing.

Raziq has categorically denied all charges of abuse, as attempts to undermine him. “When someone works well, then he finds a lot of enemies who try to ruin his name,” he told the Atlanticin 2011.

The report also details large-scale corruption, that is said to have eroded both security and confidence in the government, while stuffing the coffers of abusive strongmen. Lucrative contracts for logistics and security allowed some to maintain militias under official cover, and pay off the Taliban instead of trying to defeat them, HRW said, while other security officials were involved in drug production and trafficking.

Afghanistan is one of the most corrupt countries in the world, according to Transparency International, and the compromised justice system also badly undermines accountability, with little sense among ordinary Afghans that abusers will ever be held to account.

“Initiatives ostensibly undertaken to curb corruption and other abuses have had virtually no impact, for the same reasons there has been no progress tackling impunity in other areas,” the report said. “Officially, the United States has backed anti-corruption measures, while at the same time reportedly protecting officials accused of corruption who have been deemed vital to the war effort.”

Atta Mohammad Noor, the influential governor of northern Balkh province is one of those the report says profited from Nato projects to expand the security forces, using them to absorb and fund his own militias, hundreds of men strong. They have been accused of abuses for which HRW says Atta bears responsibility, even if he is not head of a formal chain of command. Atta denies the allegations in the report.

“The informal nature of militias can make it difficult to establish who has ultimate command responsibility for their actions,” the report says. “However, the available evidence indicates that they could not operate without Atta’s consent and have been effectively under his control, including at the time of the alleged abuses.”

It quotes him telling one villager who complained about killings by a militia group under his command in 2011. “Please forgive [the killer], it was just a mistake.”

Atta in 2011 said that two of the militias he ran were needed to secure his province because Karzai’s government refused to increase police and army ranks there. “The people who complain about militia are people who have links with the Taliban,” he told the Wall Street Journal.

Human Rights Watch called on the Afghan government and its international backers to do more to hold the security forces to account. Despite meticulous documentation of many cases of abuse, there has not been a single prosecution for torture.

Afghanistan’s new president, Ashraf Ghani, said his government would not tolerate torture and thanked HRW for the report, but did not respond to the individual allegations.